Field of the Invention
The invention relates generally to the field of dentistry, and more particularly to the field of dental restorations, implants and prostheses. The invention further relates to computer assisted and conventional systems and methods for designing and manufacturing such custom dental prosthesis.
Description of Related Art
Human teeth serve a variety of functions. Not only are they important for chewing food, but they also necessary to properly pronounce certain consonants, especially fizzle- and S-sounds. Furthermore, teeth play a major role in our personal appearance. Healthy and well aligned teeth are an ideal of beauty and appear as a cosmetic sign of youth and success.
Although various preventive measures, like frequent tooth brushing and flossing, and drinking fluoridized or iodized water are widely accepted and used, the great majority of people are sooner or later challenged with dental fillings, restorations implants, and/or other prostheses.
A major goal in dentistry is to postpone loss of teeth as long as possible. Another goal is certainly to provide comfortable prostheses with a broad scope/indication and a long lasting life-time.
Generally, the number of available restorative and prosthetic options is limited. Typically fillings, inlays, and crowns are used if the root and its embedding periodontal structure are healthy, and sufficient as support for such restorative partial prostheses. Traditionally, if the original tooth can no longer be used; the use of bridges or non-customized osseointegrated implants is indicated. In this context, several negative aspects are to be endured. In order to provide the support structure for a bridge, adjacent teeth are ground, and healthy enamel is partially destroyed. With osseointegrated implants, the gingiva-implant interface is often the cause of chronic local infection. Removable dentures, generally considered the final prosthetic option, have severe functional limitations and significant maintenance requirements.
When a tooth is partially damaged, either by caries or mechanical impact, the missing portion should in most cases be replaced. As long as a tooth provides enough structural strength to support a prosthesis, for example, an inlay or a crown, this will typically be the preferred solution. However, if the loss of tooth substance is severe, this may not be applicable. In these cases, a bridge can be applied, enduring the aforementioned negative consequences. Another option is to replace the tooth with an implant.
There are many methods or options for replacing missing teeth. Off-the-shelf or pre-shaped osseointegrated dental implants are one of the options. Osseointegration means the direct contact of the implant surface with the bone without a fibrous connective tissue interface (natural teeth are typically not in direct contact with the bone, but are connected to the bone by ligaments). The use of such dental implants includes a wide variety of implant designs and materials, use of implants in different locations in the mouth and use of a variety of surgical protocols.
Endosteal, also called endosseous implants, are placed into the bone like natural tooth roots. They can provide an anchor for one or more artificial teeth. They are the most commonly used type of implants. There are various types of endosteal implants, for example, screws, cylinders, cones, plates and blades. The generic screw, cylinder and cone types of implants are sometimes called “root-form” type. Such generic root-form implants that replace a single tooth generally consist of three parts, the actual implant-root for osseointegration, an abutment, and the artificial crown. The interfaces between the three aforementioned parts are critical in respect to the sealing quality between said three parts. Bacterial infections can be caused if the sealing is compromised in regards to its short, mid and long-term stability.
Such three-part implant designs have a first sub-gingival joint between the implant screw and the abutment. The first joint is in its height placed adjacent to the bone crest of the jaw of the implant-receiving patient. The second joint is placed iso- or supra-gingival, which means on the same vertical height of the mouth facing surface of the gingiva or beyond the trans-gingival portion of the overall implant design. The first joint between the implant screw and abutment is especially under the static and dynamic stress of mastication forces, and is identified as an area where bacteria may congregate, causing a chronic infection. This chronic infection is sometimes called “periimplantitis.”
Sometimes implant designs that actually consolidate two of said three parts (e.g., the implant-root to be osseointegrated and the abutment) are referred to as one-piece implants. Contrary hereto, the term “one-piece” implant as used hereinafter is meant to refer to the integration of all three parts: the implant root, the abutment, and the crown. The term “immediate placing” of an implant is used if the integration of the implant into the jaw occurs a short term after the extraction of a tooth. If such implants have a reasonable initial contact stability with the bone directly after being inserted (referred to as primary stability), then such implants are available for so called “immediately load”, which means that the osseo-integrative stability, or secondary stability, does not need to be developed before performing the following process steps: making an impression of the abutment part of the implant in conjunction with the gingiva and the adjacent teeth situation, then fabricating the crown, implementing the crown, and actually allowing the patient to use the implant for functional load, including mastication.
Subperiosteal implants are implants that are placed over the bone in cases where the bone has atrophied and jaw structure is limited. Subperiosteal implants are customized metal frameworks, providing the equivalent of multiple tooth roots. They can be applied in a limited area or in the entire mouth. After application, natural tissue membrane and/or bone will grow back around the implant, thus providing more stability. Posts are positioned to protrude through the gum to hold the prosthesis.
Traditionally, submerged osseointegrated dental implants are placed in bone and covered by mucosa during the immediate post-operative healing period. At four to eight months, a second surgical procedure is performed to expose the implant so it may be loaded first with various types of abutments and second with various types of dental crowns. In recent years, immediate non-submerged implant placement following tooth extraction and immediate abutment and crown loading after surgical placement has become more common.
Generic ceramic dental implants are available made from yttrium-stabilized zirconia ceramics. Although such ceramic materials are, due to its internal crystal structure and mechanisms, able to suppress micro-cracks, it has been reported in the industry that in the moist-warm environment of the human body, the long term stability of yttrium-stabilized zirconia ceramics and conventional dental implants is considered compromised to the extent that respective dental implants cannot be considered fracture-safe for the life-time expectations established.
The success rate and the in-vivo life time of non-customized osseointegrated dental implants are limited, and the surgical procedure is heavily invasive, because the bone needs to be drilled or ground in order to be adapted to the shape of the non-customized implants. Furthermore, osseointegrated implants are a limiting factor in a later orthodontic treatment. Problems relating to nerve transposition, osseous grafting, ridge augmentation, and sinus augmentation of osseointegrated dental implants, and/or to tissue health adjacent to dental implants have also been reported. Patients often complain about chronically infected periodontal structure caused by osseointegrated implants.
In cases where a tooth is not severely damaged, and would be ready to receive a partial restoration but an intra-oral repair is impossible due to access problems, or a reverse root canal treatment is required, an alternative method is the intentional re-implantation. The tooth is extracted, repaired, and re-integrated into the existing periodontal or perio-type structure of a dental patient. A disadvantage relating to such techniques is certainly that the specific tooth to be reimplanted or transplanted still needs an overall reasonable condition and prognosis to justify an intentional re-implantation and that only certain root and root canal deficiencies can be repaired this way.
U.S. Pat. No. 5,562,450 references as prior art the German application DE 27 29 969 A1, incorporated herein by reference in its entirety, which describes osseointegration of an implant that is substantially a copy of an extracted human tooth fabricated by a process involving copy milling. In order to be successfully osseointegrated, the connective tissue (e.g., ligament) remaining in the extraction socket needs to be removed by being scraped out or curetted. The '450 patent recognizes the need to create a compression pressure between the bone and the implant in order to reach reasonable primary stability of the implant and teaches to dimensionally enlarge the anatomical shape of the implant over the extracted tooth to fill the extraction socket.
Rubbert and Berndt reference in the article “Topologically Structured Surfaces and Coating Treatments for Periodontal and Osseo-Integration” published on Apr. 7, 2009, which is incorporated herein by reference in its entirety, various aspects of surface condition and treatments of dental implants and prostheses.
U.S. Pat. No. 6,099,313 discloses a dental implant for osseointegration having a bone-contact section which is root-shaped with an apical extension and an abutment described as a build-up section for fastening a crown.
All such restorative and prosthetic options and methodologies are deficient—being heavily invasive and/or limited in their respective scope. There has not been recognition, until now by the inventors, of the need for a product, systems, and methods related to the integration of dental prosthesis such as artificial tooth, bridges, or segments of the dentition that includes custom-shaped root structures, custom-shaped abutments, custom joints connecting a custom abutment to a custom-shaped root structure and/or a custom-shaped crown structure or portion of an integrated support structure, custom-made positioning and fixation integrated support structures for achieving primary stability, or a fabrication process whereby the root-shaped custom portions of the prosthesis are based on anatomical imaging data received prior to the extraction of the tooth or of the teeth of interest or directly of the alveolar situation.
In addition, recognized by the inventors, there is the need for a dental prosthesis and implementation methods which utilizes advanced ceramic materials, manufacturing technologies to increase the density and/or thickness of ceramic materials to its theoretical degree to be considered fracture-safe for use as dental implants or prostheses, metal-ceramic diffusion bonding and hot-bonding technologies to overcome bacterial issues developing on the sub-gingival joints of traditional 2-part and 3-part implant designs, and tissue engineering methods for osseointegration and perio-type integration to enhance the clinical integration of prostheses designed and manufactured according to the inventions disclosed herein as further advantageous embodiments not previously recognized until now.
The shape design of mass-produced implants shows a standardized joint between the implant and the crown portion. While the crown is usually custom-shaped to the adjacent and opposite teeth, the implant is not. Therefore, the joint between such traditional crowns and implants is non-customized. Such joints are usually shaped with standardized cylindrical, hexagonal, and conical shape portions. In order to try to obtain a positive lock between the implant and the crown, numerous standard form joints are manufactured in order to try to cover a majority of the possible crown designs. This, however, results in significant additional manufacturing costs and difficulties in inventory management. Alternatively, a smaller number of “standard” designs are manufactured designed to cover most cases. Although the smaller number helps reduce inventory management problems and manufacturing costs, it has been found too often to lead to inadequate joint connections and in an increased number of suboptimal situations, as the clinician is often provided an improperly suited connection. That is, the joint having a smaller footprint than ideal is often employed in order to allow for adjustments due to the inadequate connection. Recognized, therefore, by the inventors is the need for a custom joint which can provide a good positive lock between the implant and the crown or respectively between the implant and the abutment, which can maximize the “footprint” between the connecting pieces, and which can also be adapted to the geometrical limitations of the overall available envelope for the single tooth prosthesis.
The product, and related systems and methods provided by embodiments of the present invention or inventions comprise several independent inventive features providing substantial improvements to conventional devices and processes. The greatest benefit will be achieved for dental treatments—especially for patients requiring tooth replacement.